Semiconductor element and a producing method for the same, and a semiconductor device and a producing method for the same

ABSTRACT

A columnar bump formed of copper etc. is formed on a wiring film of a semiconductor chip through an interconnected film and an adhesive film in a wafer unit by electrolytic plating in which package formation is possible. An oxidation prevention film is formed of such as gold on an upper surface or a part of the upper surface and side surface. A wet prevention film of such as an oxide film is formed on the columnar bump side as needed. If this bump is soldered to the pad on a packaging substrate, solder gets wet in the whole region of the columnar bump upper surface and only a part of the side surface. Stabilized and reliable junction form can be thus formed. Moreover, since the columnar bump does not fuse, the distance between a semiconductor board and a packaging board is not be narrowed by solder.

This is a divisional of U.S. application Ser. No. 11/271,819, filed Nov.14, 2005, now U.S. Pat. No. 7,268,438 which is a divisional of U.S.application Ser. No. 10/359,124, now U.S. Pat. No. 7,135,770 filed Feb.6, 2003, which claims priority from Japanese Patent Application No.030334/2002, filed Feb. 7, 2002, the entire disclosure of whichapplications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor element and a producingmethod for the same, and a semiconductor device and a producing methodfor the same, more particularly relates to a bump structure of a flipchip type semiconductor element mounted face down and a producing methodfor the same, and a packaging structure thereof and a producing methodfor the same.

2. Description of the Related Art

As a connection method for connecting an electrode of a semiconductorelement and an external terminal, there are two types of methodsconsisting of a bonding wire method using a metal thin wire and a flipchip method using a solder bump formed on an electrode of asemiconductor element. And the flip chip method is considered to beadvantageous in a high-density and a high pin count tendency in recentyears. In order to raise a packaging density of a semiconductor packagein recent years, a ball grid array type semiconductor package with asolder bump formed as the external terminal is used abundantly as atechnology which can respond to a high pin count tendency, keeping aterminal pitch large. A flip chip type is adopted also as asemiconductor element mounted to a packaging board (Interposer) in manycases. As this flip chip type connection method, many are developed. Forexample a connection method referred as a control coraps chip connection(C4) is mentioned first.

FIG. 35 is a cross-sectional view showing a conventional structure of aflip chip type semiconductor element. As shown in FIG. 35, on asemiconductor substrate 1, an electrode 2 which is connected to internalwiring and a cover film 3 having an opening on the electrode 2, isformed. And on the electrode 2, a solder bump 20 is formed through aninterconnected film 4 and an adhesive film 5. As for a method forforming a solder bump 20, it is common to form a hemispherical bump bysupplying solder by various methods such as an evaporation method, anelectrolytic plating method, a solder paste printing method, and asolder ball loading and supplying method, and solder reflow processusing flux.

FIG. 36 is a cross-sectional view showing a conventional flip chippackaging structure of flip chip type semiconductor element. On a pad 14of a wiring substrate (Interposer) 12 wherein the pad 14 and a solderresist film 13 are formed on the surface, solder is supplied beforehand.Then, after applying flux, a semiconductor element is carried on thewiring substrate 12. And connection between bump 20 and pad 14 iscompleted by solder reflow process to form a solder fillet 11.Subsequently, the crevice between the wiring substrate 12 and asemiconductor substrate 1, which is not shown, is filled up withunderfill resin.

A method for using bonding wire and forming a gold stud bump on theelectrode of a semiconductor chip, in addition to a solder bump, and amethod for forming a gold bump by electrolytic gold plating areconventionally known. These bumps are adhered to metal films such asgold plating, silver/tin solder, and indium/tin/lead solder formed inthe wiring substrate side.

For securing reliability, filling up the crevice between a semiconductorchip and a wiring substrate with underfill resin after flip chipmounting is carried out. When resin filling is performed, keeping thecrevice between a semiconductor chip and a wiring substrate large ispreferable for performing good filling without generating void. However,if a solder bump is required to be formed highly in height so as to bemelted on an electrode and shaped in hemisphere form, the amount ofsolder to be supplied should be increased. This makes it possible toshort circuit to an adjoining solder bump, between the electrodes havinga fine pitch. Therefore, it is becoming difficult to form a solder bumpwith height on an electrode with advance of a fine pitch tendency. Onthe other hand, since, as for the fine pitch tendency, filling resinstream is narrowed superficially, the difficulty of filling of underfillresin is accelerated by fine pitch.

A method for forming a solder bump by an evaporation method and a solderpaste printing method involves an increased manufacturing cost, since adurability of a mask is scarce as well as requiring the mask.

Also, a solder ball supplying method involves a comparatively high costof the solder ball per se, and needs equipment wherein a solder ball isaligned in a required layout and carried on a semiconductor chip. Sincepackage loading in a wafer unit is difficult, the bump formation cost astotal becomes high. Moreover, manufacture of solder ball with furthersmall diameter corresponding to a fine pitch is difficult. Then, thesmaller the required ball size (diameter) becomes, the more themanufacturing yield falls, incurring an influence on high cost.

Furthermore, when there is an electrode arranged on a memory cell, andwhen solder is used as a bump material, alpha rays generated from aradioactive element contained in a lead which constitutes solder or tinmay cause a soft error.

Also, there are the plating bump and stud bump using gold. However,problem such that cost of gold materials is high is posed. There is alsoraised a problem such that the more the number of bumps increases, themore formation cost increases also, in order to carry out individualformation in a gold stud bump.

Furthermore, when solder junction of the bump which used gold plating iscarried out, since gold has a good wettability, solder is getting wetupwardly on side surface and enters from the interface of an electrodeand gold plating. This may result in the fall of interface intensity, orexfoliation in the end, involving the problem on reliability.

Also, a soldering technique by use of a plating bump using copper isalso proposed. For example, after forming a copper bump by anelectrolytic plating method, forming the polyimide film on asemiconductor board so that the upper half of the copper bump may beexposed, and forming a solder film on the copper bump by dipping methodis disclosed in JP-A-3-22437. However, with a flip chip coated with athick resin film in this way, when mounted on a wiring substrate, itbecomes difficult to be filled up with underfill resin. In addition,since an adhesion nature of the copper bump and the polyimide film islow, unless processing special to the copper bump side is performed,solder easily gets wet, spreading to the electrode. Problem onreliability is thus raised similarly to the case of a gold bump.

SUMMARY OF THE INVENTION

An object of the present invention is to secure full distance betweenchip and substrate even if an electrode has a fine pitch.

The other object of the present invention is to provide a bump structureof a flip chip which can be created at low cost.

The other object of the present invention is to provide a packagingstructure of a low possibility of causing the reliability fall such as asoft error or pad exfoliation.

A semiconductor element according to the present invention comprises acolumnar projection which serves as a bump and is formed on an electrodethrough an interconnected film or an adhesive film. An upper surface ofsaid columnar projection is coated with, or an upper surface and upperportion of a side surface of the aforementioned columnar projection arecoated with a cap film which is excellent in wettability is provided.

Also, a semiconductor element according to another aspect of the presentinvention comprises a columnar projection which serves as a bump and isformed on an electrode through an interconnected film or an adhesivefilm. A wet prevention film is formed at a part at least close to theelectrode of the side surface of the columnar projection.

Also, a method of producing a semiconductor element according to thepresent invention, comprising the steps of:

forming a metal film serving as a plating electrode on the whole part ofa semiconductor substrate having an electrode formed thereon;

forming a resist film having an opening in the position of saidelectrode on said metal film;

depositing a high conductivity metal in columnar form to form a columnarprojection by electrolytic plating;

removing said resist film;

etching to remove said metal film by using said columnar projection as amask; and

forming a wet prevention film on the surface of said columnarprojection.

Also, a method of producing a semiconductor element according to anotheraspect of the present invention comprises the steps of:

forming a resist film on a semiconductor substrate, said resist filmhaving an opening in the position of an electrode formed on saidsemiconductor substrate;

conducting an activation processing to electroless plating to form anactivation film on said resist film;

removing said activation film on said resist film;

depositing a high conductivity metal in said opening by electrolessplating to form a columnar projection;

removing said resist film; and

forming a wet prevention film on the surface of said columnarprojection.

A semiconductor device according to the present invention comprises: aconductive columnar projection formed on the electrode of asemiconductor element and is soldered to a pad on a wiring substrate. Atleast a part of the side surface of said columnar projection is coatedwith a wet prevention film.

Also, a semiconductor device according to another aspect of the presentinvention comprises: a conductive columnar projection formed on anelectrode of the semiconductor element and is soldered to a pad of awiring substrate. The soldering part of said conductive columnarprojection is limited to the upper surface of said columnar projection.

Also, a semiconductor device according to another aspect of the presentinvention comprises: a conductive columnar projection formed on anelectrode of the semiconductor element and is soldered to a pad of awiring substrate. Said columnar projection is soldered through a metalfilm excellent in soldering wettability as well as having a difficultyin oxidation which is formed on the upper surface of said columnarprojection or the upper portion or upper surface of said columnarprojection side surface.

Also, a semiconductor device according to another aspect of the presentinvention comprises: a conductive columnar projection formed on anelectrode of the semiconductor element and is connected to a pad on awiring substrate. An upper surface of said columnar projection and asurface of a pad of said wiring substrate are joined through a metalfilm which is excellent in soldering wettability as well as havingdifficulty in oxidation.

Also, a method of producing a semiconductor device according to thepresent invention comprising the steps of:

providing a thermosetting resin having a flux activity effect to the tipend of a columnar projection formed on the electrode of a semiconductorelement;

aligning said columnar projection and a pad of the wiring substratewhich was supplied with a predetermined quantity of solder; and

heating and soldering only the tip part of said columnar projection tothe pad of said wiring substrate.

A method of producing a semiconductor device according to another aspectof the present invention comprises the steps of:

supplying a flux on the tip end of the columnar projection formed on anelectrode of a semiconductor element;

aligning said columnar projection and a pad of a wiring substratesupplied with a predetermined quantity of solder;

heating and soldering only the tip part of said columnar projection to apad of said wiring substrate; and

cleaning and removing said flux.

Also, a method of producing a semiconductor device according to anotheraspect of the present invention comprises the steps of:

supplying a thermosetting resin having the flux activity effect on a padof a wiring substrate;

aligning a columnar projection formed on an electrode of a semiconductorelement and having a solder film on the tip part, and a pad of saidwiring substrate; and

heating and soldering only the tip part of said columnar projection to apad of said wiring substrate.

Also, a method of producing a semiconductor device according to anotheraspect of the present invention comprises the steps of:

supplying a flux on a pad of a wiring substrate;

aligning a columnar projection formed on an electrode of a semiconductorelement and having a solder film on a tip end part, and a pad of saidwiring substrate;

heating and soldering only the tip part of said columnar projection to apad of said wiring substrate; and

cleaning and removing said flux.

Also, a method of producing a semiconductor device according to anotheraspect of the present invention comprises the steps of:

cleaning a tip surface of a columnar projection formed on an electrodeof a semiconductor element and a pad surface of a wiring substrate by aphysical shock of an inactive gas excited by plasma;

aligning said columnar projection and a pad of said wiring substrate;and

pressurizing between said semiconductor element and said wiringsubstrate to adhere said columnar projection and said pad.

In the present invention, connection system between a semiconductorelement and a wiring substrate is different from a conventionalconnection system wherein solder is connected with each other or goldstud bump and a solder of the wiring substrate side are connected.However, in this invention, a columnar bump of a semiconductor elementside and a pad of the wiring substrate are connected through a littlequantity of solder, or directly connected without through solder. Inaddition, in this invention, even when connection is made by solder,contact of a columnar bump and solder is limited to an upper surface ofthe columnar bump or only a little bit part of the upper surface and theside surface thereof. A columnar bump is formed by an electrolyticplating method etc. using a metal which is not fused at solderingtemperature, and since it is not rounded by reflow, a comparatively highbump can be formed in relation to a bottom size. Moreover, when asemiconductor chip is carried on a wiring substrate, a columnar bumpdoes not fuse but maintain the form in early stages of formation. Thisallows the distance between a wiring substrate and a semiconductor chipto be fully secured. This further allows underfill resin filling to beeasily and highly reliably performed after flip chip connection. Namely,as for a connection of solders wherein when having a fine pitch, alongwith a smaller diameter size of a bump, crevice reduction of asemiconductor chip and a wiring substrate is generated, and workabilityand reliability are predominantly gained.

A batch processing of a wafer unit is possible. And this will bementioned, for example, as other features of forming a columnar bumpusing an electrolytic plating method or the electroless plating method.Whereby, it becomes possible to manufacture at low cost compared with aconventional ball loading supplying method. Also, in case of using athermosetting resin which has a flux activity effect instead of the fluxused for the purpose of the oxide film removal on the surface of a bumpat the time of packaging onto the wiring substrate of a semiconductorchip, cleaning process can be deleted. This contributes to cleaningprocess reduction to allow cost cut or no cleaning residue.Consequently, an improvement effect in reliability is gained.

Moreover, since reduction or deletion of the amount of the solder usedis possible, the reduction or zeroing of alpha dose which is one of thecauses of malfunction is possible. This contributes to an improvement inreliability.

Also, according to this invention, solder does not get wet upwardly asfar as a columnar base of a bump at the time of packaging. The interfaceexfoliation by the solder-coming-in onto the interface of aninterconnected film/adhesive film, or an adhesive film/bump can beprevented, and improvement in reliability can be aimed at.

Moreover, when making a junction form in which solder gets wet upwardlyas far as a part of the side surface of a columnar bump, a process isincreased when forming a bump. However, when the contact surface area ofa columnar bump and solder is widened, stress is distributed andjunction part reliability can be raised.

In a semiconductor device producing method for this invention, a capfilm or a solder plating film is formed on an upper surface of thecolumnar bump, or in a part of an upper surface or side surface thereof.Therefore, a junction form wherein solder possibly covers the wholeupper surface of the columnar bump, or solder possibly covers the holeupper end portion is stably made up. Whereby, the strength fall injunction between the columnar bump and adhesive films or formation of astress concentration part can be prevented, and a reliable junction partcan be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a first embodiment of asemiconductor element of this invention.

FIG. 2 is a cross-sectional view of a second embodiment of asemiconductor element of this invention.

FIG. 3 is a cross-sectional view of a third embodiment of asemiconductor element of this invention.

FIG. 4 is a cross-sectional view of a fourth embodiment of asemiconductor element of this invention.

FIG. 5 is a cross-sectional view of a fifth embodiment of asemiconductor element of this invention.

FIG. 6 is a cross-sectional view of a sixth embodiment of asemiconductor element of this invention.

FIG. 7 is a cross-sectional view of a seventh embodiment of asemiconductor element of this invention.

FIG. 8 is a cross-sectional view of a first embodiment of a producingmethod for a semiconductor element of this invention.

FIG. 9 is a cross-sectional view of a second embodiment of a producingmethod for a semiconductor element of this invention.

FIG. 10 is a cross-sectional view of a third embodiment of a producingmethod for a semiconductor element of this invention.

FIG. 11 is a cross-sectional view of a fourth embodiment of a producingmethod for a semiconductor element of this invention.

FIG. 12 is a cross-sectional view of a fifth embodiment of a producingmethod for a semiconductor element of this invention.

FIG. 13 is a cross sectional view of a first embodiment of asemiconductor device.

FIG. 14 is a cross sectional view of a second embodiment of asemiconductor device.

FIG. 15 is a cross sectional view of a third embodiment of asemiconductor device.

FIG. 16 is a cross sectional view of a fourth embodiment of asemiconductor device.

FIG. 17 is a cross sectional view of a fifth embodiment of asemiconductor device.

FIG. 18 is a cross sectional view of a sixth embodiment of asemiconductor device.

FIG. 19 is a cross-sectional view of a first embodiment of a producingmethod for a semiconductor device of this invention.

FIG. 20 is a cross sectional view of a second embodiment of a producingmethod for a semiconductor device of this invention.

FIG. 21 is a cross sectional view of a third embodiment of a producingmethod for a semiconductor device of this invention.

FIG. 22 is a cross sectional view of a fourth embodiment of a producingmethod for a semiconductor device of this invention.

FIG. 23 is a cross sectional view of a fifth embodiment of a producingmethod for a semiconductor device of this invention.

FIG. 24 is a cross sectional view of a sixth embodiment of a producingmethod for a semiconductor device of this invention.

FIG. 25 is a cross sectional view of a seventh embodiment of a producingmethod for a semiconductor device of this invention.

FIG. 26 is a cross sectional view of a eighth embodiment of a producingmethod for a semiconductor device of this invention.

FIG. 27 is a cross sectional view of a ninth embodiment of a producingmethod for a semiconductor device of this invention.

FIG. 28 is a cross sectional view of a tenth embodiment of a producingmethod for a semiconductor device of this invention.

FIG. 29 is a cross sectional view of a eleventh embodiment of aproducing method for a semiconductor device of this invention.

FIG. 30 is a cross sectional view of a twelfth embodiment of a producingmethod for a semiconductor device of this invention.

FIG. 31 is a cross sectional view of a thirteenth embodiment of aproducing method for a semiconductor device of this invention.

FIG. 32 is a cross sectional view of a fourteenth embodiment of aproducing method for a semiconductor device of this invention.

FIG. 33 is a cross sectional view of a fifteenth embodiment of aproducing method for a semiconductor device of this invention.

FIG. 34 is a cross sectional view of a sixteenth embodiment of aproducing method for a semiconductor device of this invention.

FIG. 35 is a cross-sectional view of a conventional example of asemiconductor element.

FIG. 36 is a conventional view of a conventional example of asemiconductor device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described belowwith reference to the accompanying drawings. FIG. 1 is a cross-sectionalview showing a first embodiment of a semiconductor element according tothe present invention. As shown in FIG. 1, on a semiconductor substrate1, an electrode 2 connected to an internal circuit is formed. And on thesemiconductor substrate 1 is covered with a cover film 3 which has anopening on the electrode 2. On the electrode 2, a columnar bump 6composed of such as copper through an adhesive film 5 composed of anadhesive film 4 which composed of such as titanium (Ti) and copper (Cu),is formed. A wet prevention film 7 wherein adhesion of solder andwetting upwardly are prevented is formed on the side surface of thecolumnar bump 6. The columnar bump 6 may be formed using copper alloy,or nickel and nickel alloy other than copper.

FIG. 2 is a cross-sectional view showing a second embodiment of asemiconductor element of this invention. In FIG. 2, the portions of thesame designation as those in FIG. 1 used for the explanation so far aredesignated the same reference numbers, omitting and simplifying theoverlapping explanation (similarly omitted in other embodiments).Difference from the first embodiment shown in FIG. 1 of this embodimentresides in the formation such that a cap film 8 which prevents thecolumnar bump 6 from oxidation and composed of gold (Au) whichdemarcates the domain of getting wet at the time of the soldering isformed.

FIG. 3 is a cross-sectional view showing the third exemplary embodimentof a semiconductor element of this invention. Difference from the firstembodiment shown in FIG. 1 of this invention resides in the formationsuch that a cap film 8 composed of a gold (Au) which prevents a columnarbump 6 from oxidation and demarcates a domain of getting wet at the timeof soldering is formed on an upper surface or on a part of the sidesurface of the columnar bump 6, and a wet prevention film 7 is deletedfrom the side surface portion of the columnar bump 6 having the cap film8 formed thereon.

As for a second and third embodiment, when a cap film 8 is formed withmaterial with fully high wettability to a columnar bump, a wetprevention film can be omitted. Moreover, a cap film may be formed usinga resin material using a resin material known as a pre-flux coatmaterial which fuses by flux at the time of soldering, replacing ametallic cap film.

FIG. 4 is a cross-sectional view showing a fourth embodiment of asemiconductor element of this invention. Difference from a firstembodiment shown in FIG. 1 of this embodiment resides in a formation inwhich a planting layer 9 is formed on an upper surface of a columnarbump 6.

FIG. 5 is a cross-sectional view showing a fifth embodiment of asemiconductor element of this invention. Difference from a firstembodiment shown in FIG. 1 of this embodiment resides in a formation inwhich a plating film 9 is formed on a upper surface or a part of theside surface of a columnar bump 6, and a wet prevention film 7 isdeleted from the side portion of the columnar bump 6 having solderplating film 9 formed thereon.

FIG. 6 is a cross-sectional view showing a sixth embodiment of asemiconductor element of this invention. Difference from a fourthembodiment shown in FIG. 4 of this embodiment resides in a formation inwhich a thin golden layer 10 is formed on an upper surface of a solderplating layer 9.

FIG. 7 is a cross-sectional view showing a seventh embodiment of asemiconductor element of this invention. Difference from a fifthembodiment shown in FIG. 5 of this embodiment resides in a formation inwhich a thin gold film 10 is formed on an upper surface or side surfaceof a solder plating film 9.

FIGS. 8A to 8E are cross-sectional views showing order of a producingmethod for a semiconductor element of this invention. As shwn in FIG.8A, an electrode 2 and a front surface of a cover film 3 of asemiconductor substrate 1 are coated with an interconnected film 4 andan adhesive film 5, by sputtering method etc. The interconnected film 4is preferably formed with titanium. However, a single layer containingtitanium alloys such as nitriding titanium, titanium/tungsten alloy, inaddition to titanium or multiple layers, and a single layer containingchromium, chromium/copper alloy, or multiple layers may be substituted.The adhesive film 5 is preferably formed with copper. However, ifadhesion power with a columnar bump (copper plating film etc) which isformed other than copper, is strong and electrical resistance is in therange of a small metal, composition substance is not limited.

Next, as shown in FIG. 8B, a plating resist film 19 having a thicknessmore than a height of the bump which should be formed and has an openingon an electrode 2, is formed using photoresist etc. Electrolytic platingis performed by making this into a mask, and a columnar bump 6 isformed.

Next, as shown in FIG. 8C, the plating resist film 19 is removed byashing etc, and etching removal of the adhesive film 5 and theinterconnected film 4 in an exposure form is carried out, using thecolumnar bump 6 as a mask.

Subsequently, as shown in FIG. 8D, heat-treatment is performed inoxidizing atmosphere, so as to obtain a wet prevention film 7 on asurface of the columnar bump 6.

Next, as shown in FIG. 8E, after exposed to the plasma of inactive gassuch as argon (Ar), removal of the only wet prevention film of an uppersurface of the columnar bump 6 is carried out.

Replacing a method wherein unnecessary wet prevention film is exposed tothe plasma of inactive gas to be removed, after covering the part by amask where a wet prevention film is not necessary to be formed,oxidation processing is performed, and the mask may be removedthereafter. Wet prevention film 7 may be formed with a silicon oxidefilm or a silicon nitride film, etc. deposited, by a film formationtechnology such as plasma CVD method. In this case also, after a wetprevention film is formed in front, unnecessary wet prevention film isexposed to the plasma of inactive gas to be removed. Or after a portionwhere a wet prevention film does not needed to be formed is covered witha mask, films are formed, and the mask may be removed thereafter. Incase that a wet prevention film 7 is formed by a film formationtechnology such as CVD method, a wet prevention film 7 with filmthickness almost equivalent to a side surface of the columnar bump 6 isobtained on the side surface of an interconnected film 4 and a adhesionfilm 5.

FIGS. 9A to 9E are cross-sectional views of a process order showing asecond embodiment of a producing method for a semiconductor element ofthis invention. In this embodiment, up to the process shown in FIG. 9Bis the same as the first embodiment.

Then, as shown in FIG. 9C, a cap film 8 is formed on an upper surface ofa columnar bump 6 by an electrolytic plating method or electrolessplating method. As shown in FIG. 9D, a plating resist film 19 and anadhesive film 4 and an interconnected film 5 thereunder are removed.Then, a wet prevention film 7 is formed on the side surface of thecolumnar bump 6 by heat-treatment in the atmosphere of oxidizing.

FIGS. 10A to 10F are cross-sectional views of a process order showing athird embodiment of a producing method for a semiconductor element ofthis invention. In this embodiment, up to a process shown in FIG. 10B isthe same as the first embodiment. Then, half etching is performed to theplating resist film 19, and a part of a columnar bump 6 side is exposedas shown in FIG. 10C.

Subsequently, a cap film 8 is formed on an upper surface or upper sideof a columnar bump 6 by an electrolytic plating method or an electrolessplating method, as shown in FIG. 10D. After removing the plating resistfilm 19, an interconnected film 4 thereunder, and an adhesive film 5, bybeing subjected to heat-treatment in the atmosphere of oxidizing, a wetprevention film 7 is formed on the columnar bump 6 side surface, asshown in FIG. 10F.

Referring to a second and third embodiment, a wet prevention film 7 canbe formed by use of a film formation technology such as a plasma CVDmethod. At that time, after covering a no film formation domain using amask, films can be formed. The same is said of other embodiments.

In a second and third embodiment, gold is advantageously used for thematerial of the cap film 8. However, any material which is excel insolder wettability, and can prevent an oxidation of a columnar bump, canbe used. For example, such as gold alloy, tin, indium or palladium canbe mentioned as available.

FIGS. 11A to 11E are cross-sectional views of a process order showing afourth embodiment of a producing method for a semiconductor element ofthis invention. In this embodiment, up to a process shown in FIG. 11B isthe same as first embodiment. A solder plating film 9 is formed on anupper surface of a columnar bump 6 by an electrolytic plating methodsubsequently to a columnar formation of a bump. [FIG. 11C]. Next, aplating resist film 19, an interconnected film 4 thereunder, and anadhesive film 5 are removed [FIG. 11D]. Then, after subjected toheat-treatment in oxidizing atmosphere to form a wet prevention film 7on a surface of a columnar bump 6, sputter removal of oxide film iscarried out on a solder plating film 9 [FIG. 11E].

FIG. 12A to F is a cross-sectional view of a process order showing afifth embodiment of a producing method for a semiconductor element ofthis invention. This embodiment is the same as a fourth embodiment shownin FIG. 11 except for half etching process (FIG. 12C) before forming asolder plating film 9.

In a fourth and fifth embodiment, a solder plating film 9 can be formedusing tin/eutectic lead alloy, but not limited thereto but a materialused as a solder material is employable as needed. Also, a solder whichdoes not contain a lead is preferably adopted. Moreover, in the fourthand fifth embodiment, after formation of the solder plating film 9,electrolytic or electroless plating is performed successively. A metalfilm may be formed thinly on the solder plating film 9 as shown in FIG.6 and FIG. 7.

A bump may be formed by an electoless plating method. In this case,patterning of an interconnected film and an adhesive film is performedin a state shown in FIG. 9A so as to form a resist film having anopening on a bump formation part. Then, an activation processing by suchas zinc is performed, an unnecessary activity layer is removed asneeded, and an electroless plating of such as nickel is performed toform a bump, before resist film is removed. The bump may be formeddirectly on an electrode without forming an interconnected film and anadhesive film.

FIG. 13 is a cross-sectional view showing a first embodiment of asemiconductor device of this invention. The semiconductor elementaccording to this invention is carried on a wiring substrate 12 whereina pad 14 and a solder resist film 13 are formed on the surface. In thisembodiment, a columnar bump 6 of the semiconductor element is joined toa pad 14 on the wiring substrate 12 by solder fillet 11 only on theupper surface (in this specification, the opposite side to an electrode2 of a columnar bump is referred as an upper surface).

FIG. 14 is a cross-sectional view of a second embodiment of asemiconductor device of this invention. Difference from a firstembodiment shown in FIG. 13 of this embodiment resides in a formationsuch that a cap film 8 is formed on an upper surface of a columnar bump6.

FIG. 15 is a cross-sectional view of a third embodiment of asemiconductor device of this invention. Difference from a firstembodiment shown in FIG. 13 of this embodiment resides in a formationsuch that a columnar bump 6 of a semiconductor element is joined to asolder fillet 11 also, not only in the upper surface but in a part ofits side surface.

FIG. 16 is a cross-sectional view showing a fourth embodiment of asemiconductor device of this invention. Difference from a thirdembodiment shown in FIG. 15 of this embodiment resides in a formationsuch that a cap film 8 is formed on an upper surface of columnar bump 6of a semiconductor element or a part of its side surface.

FIG. 17 is a cross-sectional view showing a fifth embodiment of asemiconductor device of this invention. In this embodiment, a columnarbump 6 of a semiconductor element is directly joined to a pad 14 on awiring substrate 12 through no aid of solder.

FIG. 18 is a cross-sectional view showing a sixth embodiment of asemiconductor device of this invention. In this embodiment, a columnarbump 6 of a semiconductor element is joined to a pad 14 on a wiringsubstrate 12 through a cap film 8.

FIGS. 19A to 19C is a cross-sectional view of a process order showing afirst embodiment of a producing method for a semiconductor device ofthis invention. This embodiment relates to a packaging method for asemiconductor element shown in FIG. 1. Flux 15 is supplied to a tip partof a columnar bump 6 of a semiconductor element. In addition, a solderfilm 16 is formed on a pad 14 of a wiring substrate 12 beforehand, asshown in FIG. 19A. After aligning a semiconductor element so that thecolumnar bump 6 may be located on a pad 14, a semiconductor element iscarried on the wiring substrate 12, to be subjected to solder reflowprocess, and a columnar bump 6 is joined to a pad 14 through solderfillet 11, as shown in FIG. 19 B. Then, cleaning and removing flux 15 isperformed before filled up with underfill resin 17, and cured, as shownin FIG. 19C.

A solder film 16 may be a solder paste layer, or may be a solder reflowlayer. Tin/eutectic lead solder is preferably used for solder film 16,but is not limited thereto. Tin/lead (except for eutectic), tin/silver,tin/copper, tin/zinc, and alloy in which other addition elements areadded to such material, further can be used.

In this embodiment, flux 15 was applied to a columnar bump 6 sidesurface. Instead of this, flux 15 may be applied on a solder film 16 ora pad 14. The same thing is said about other embodiment. Also, in asoldering process of this embodiment, a semiconductor element ispreferably pressed to a wiring substrate side surface by predeterminedpressure. Whereby, constriction structure which collects stress can beavoided.

FIGS. 20A to 20C are cross-sectional views of a process order showing asecond embodiment of a producing method for a semiconductor device ofthis invention. This embodiment relates to a packaging method for asemiconductor element shown in FIG. 2. Difference from a firstembodiment shown in FIG. 19 resides in a formation such that a cap film8 is formed on an upper surface of a columnar bump 6. Incidentally, whenthe cap film 8 is formed with a resin film which melts in a thin gold(or gold alloy) film or flux, since the cap film 8 melts in solder orflux at the time of solder melting, this cap film 8 disappears aftersolder reflow process is over as shown in FIGS. 20B′ and 20C′.

FIGS. 21A to 21C are cross-sectional views of a process order showing athird embodiment of a producing method for a semiconductor device ofthis invention. This embodiment relates to a packaging method for asemiconductor element shown in FIG. 4. Flux 15 is applied to a tip partof a columnar bump 6, as shown in FIG. 21 A having a solder plating film9 formed only on the upper surface thereof, a semiconductor element iscarried on a wiring substrate after alignment, and solder reflow processproduces a solder fillet 11, as shown in FIG. 21B. Subsequent processingis the same as that of the first embodiment shown in FIG. 19. FIGS. 22Ato 22C are cross-sectional views of a process order of a fourthembodiment of a producing method for a semiconductor device of thisinvention. This embodiment relates to a packaging method for asemiconductor element shown in FIG. 1. Difference from a firstembodiment shown in FIG. 19 resides in a formation such that instead offlux, a thermosetting resin (henceforth, activity resin) having fluxactivity effect is used for soldering. Namely, activity resin 18 issupplied to a tip part of a columnar bump 6 of a semiconductor element,and further, a solder film 16 is formed on a pad 14 of a wiringsubstrate 12 beforehand, as shown in FIG. 22A. After alignment, asemiconductor element is carried on a wiring substrate 12, thensubjected to solder reflow process, and a columnar bump 6 is joined to apad 14 through solder fillet 11, as shown in FIG. 22B, then filled upwith underfill resin 17 and cured, with activity resin 18 left, as shownin FIG. 22C.

In this embodiment, activity resin 18 is applied to a columnar bump 6side surface. However, replacing this, application may be carried outonto a solder film 16 or a pad 14. The same is said of otherembodiments.

FIGS. 23A to 23C are cross-sectional views of a process order showing afifth embodiment of a producing method for a semiconductor device ofthis invention. This embodiment relates to a packaging method for asemiconductor element shown in FIG. 2. Difference from a secondembodiment shown in FIG. 20 resides only in soldering by use of activityresin 18, to thereby omit a detailed explanation. Incidentally, when acap film 8 is formed of a thin gold film (or gold alloy) or a resin filmwhich dissolves in flux, the cap film 8 melts in solder or activityresin at the time of solder fusion. Hence, after solder reflow processis over, as shown in FIGS. 23B′ and C′, the cap film 8 disappears.

FIGS. 24A to 24C are cross-sectional views of a process order showing asixth embodiment of a producing method for a semiconductor device ofthis invention. This embodiment relates to a packaging method for asemiconductor element shown in FIG. 4. Difference from a thirdembodiment shown in FIG. 21 of this embodiment resides in only solderingby use of an activity resin 18 replacing flux. Therefore, a detailedexplanation will be omitted.

FIGS. 25A to 25C are cross-sectional views of a seventh embodiment of aproducing method for a semiconductor device of this invention. Thisembodiment relates to a packaging method for a semiconductor elementshown in FIG. 3. Flux 15 is supplied to a tip part of a columnar bump 6having a cap film 8 formed on a part of upper surface and side surface,forming a solder film 16 on a pad 14 of a wiring substrate 12beforehand. [FIG. 25A]. After alignment, a semiconductor element iscarried on a wiring substrate 12, and subjected to reflow solderingprocess. Then, solder gets wet upwardly along a cap film 8 so as toallow a fillet 11 to be formed as far as a columnar bump 6 side surface,a shown in FIG. 25B. And cleaning and removing a flux 15 is performed,before filled up with an underfill resin 17 and cured, as shown in FIG.25C. Incidentally, when the cap film 8 is formed with a resin film whichmelts in a thin gold (or gold alloy) film or flux, since the cap film 8melts in solder or flux at the time of solder melting, it disappearsafter solder reflow process is over as shown in FIGS. 25B′ and 25C′.

FIGS. 26A to 26C are cross-sectional views of a process order showing aneighth embodiment of a producing method for a semiconductor device ofthis invention. This embodiment relates to a packaging method for asemiconductor element shown in FIG. 5. Since this embodiment is the sameas a third embodiment shown in FIG. 21 except for the point that thesolder plating film is formed on a part of a columnar bump 6 sidesurface, detailed explanation is omitted.

FIGS. 27 A to 27C are cross-sectional views of a process order showing aninth embodiment of a semiconductor element of this invention. Thisembodiment relates to a packaging method for a semiconductor elementshown in FIG. 3. Difference from a seventh embodiment shown in FIG. 25of this embodiment resides only in soldering by use of an active resin18 replacing flux, to thereby omit a detailed explanation. Incidentally,when a cap film 8 is formed with a resin film which melts in a thin gold(or gold alloy) film or flux, since the cap film 8 melts in solder orflux at the time of solder melting, this cap film 8 disappears aftersolder reflow process is over as shown in FIG. 27 B′ and C′.

FIGS. 28A to 28C are cross-sectional views of a process order showing atenth embodiment of a producing method for a semiconductor device ofthis invention. This embodiment relates to a packaging method for asemiconductor element shown in FIG. 5. Difference from an eighthembodiment shown in FIG. 26 of this embodiment resides only in solderingby use of an active resin 18, replacing flux, thereby to omit a detailedexplanation.

In seventh embodiment to eleventh embodiment, referring to an oxide filmremoval capability of flux or an activity resin, and the supply amount,in order to acquire a fillet form where solder gets wet upwardly to apart of a columnar bump side, which is a characteristic structure ofthis embodiment, adjustment is needed to be preferably carried out asneeded.

FIGS. 29 A to 29C are cross-sectional views of a process order showingan eleventh embodiment of a producing method for a semiconductor deviceof this invention. The upper surface or upper portion of the side of acolumnar bump 6 of a semiconductor element used in this embodiment, iscoated with a cap film 8′ composed of a resin material which melts influx at the time of soldering. A junction part of the columnar bump 6 isnot oxidized in an ambient atmosphere, and is maintained in a cleanstate. Flux is applied beforehand on a solder film 16 formed on a pad 14of a wiring substrate 12, as shown in FIG. 29A. After alignment asemiconductor element so that a columnar bump 6 may be located on a pad14, if a semiconductor element is carried on the wiring substrate 12 andsubjected to solder reflow process, a cap film 8′ melts, junction partof the columnar bump 6 is exposed, and the columnar bump 6 is solderedto the pad 14, as shown in FIG. 29 B. Then, cleaning and removing flux15 is performed, before filled up with underfill resin 17 and cured, asshown in FIG. 29 C.

Flux 15 was applied to a solder film 16 in this embodiment. However,replacing this, application may be carried out onto a columnar bump 6side surface. Also, replacing flux, an activity resin having a fluxaction may be used.

In a seventh embodiment to a eleventh embodiment, referring to an oxidefilm removal capability and a supply amount of flux or activity resin,it is necessary to adjust suitably to obtain a fillet form in whichsolder gets wet upwardly as far as a part of a columnar bump side, whichis a characteristic form of this embodiment. That is, what is importantto obtain a necessary junction form in a semiconductor devicemanufacture process of this invention is whether a suitable quantity issupplied by flux, while activity resin has a suitable removal capabilityof oxide film. If oxide film removal capability is too strong, soldergets wet upwardly as far as a root of a columnar bump which is notwanted to be wet and assumes the form in which solder wraps the columnarbump. Then, such a possibility arises as solder advancing between thecolumnar bump and an adhesive film, or an adhesive film and aninterconnected film, reducing adhesion intensity, and resulting inexfoliation. Also, if oxide film removal capability is too weak, stablemetal junction is not carried out in the interface of solder with acopper bump, with a result that connecting becomes poor. Accordingly, itis important to select flux or activity resin with suitable oxide filmremoval capability and supply a suitable quantity uniformly.

However, in soldering of a semiconductor element of this invention, fluxor activity resin is not indispensable, and when a junction interfaceand a solder film surface are kept clean enough, the semiconductorelement can also be soldered without using these. The following twelfthand thirteenth embodiment relate to a soldering method for not usingflux or activity resin.

FIGS. 30A to 30C are cross-sectional views of a process order showing atwelfth embodiment of a producing method for a semiconductor device ofthis invention. This embodiment relates to a packaging method for asemiconductor element shown in FIG. 7. In this embodiment, while goldfilm 10 is formed on the surface of the solder plating film 9 providedon an upper part of a columnar projection 6, gold film 10 is formed alsoon a pad 14, as shown in FIG. 30 A. By forming these gold films, thesurface of a solder plating film 9 and a pad 14 is held in a clean statewithout oxidizing. After aligning a semiconductor element so that thecolumnar bump 6 may be located on the pad 14, if a semiconductor elementis carried on a wiring substrate 12 and subjected to solder reflowprocess, the gold film 10 melts in solder and the columnar bump 6 isjoined to the pad 14 through solder fillet 11, as shown in FIG. 30B,then filled up with the underfill resin 17 thereafter and cured, asshown in FIG. 30C.

In this embodiment, gold films 10 are formed on both solder plating film9 and pad 14. However, only either of them may be sufficient. In thiscase, a series of process of storage, conveyance, and packaging iscarried out in non-oxidizing atmosphere, such as a vacuum and reductiveatmosphere. Whereby, it is important that the junction part surface ismade not to be polluted.

FIGS. 31A to 31C is a cross-sectional view of a process order showing athirteenth embodiment of a producing method for a semiconductor deviceof this invention. The top surface and upper part of the side of acolumnar bump 6 of semiconductor element of the embodiment of thisinvention is covered by thin gold film 10. Gold film 10 is formed alsoon a solder film surface 16 of a pad 14 as shown in FIG. 31A. Afteralignment, a semiconductor element is carried on a wiring substrate 12and subjected to solder reflow process, the gold film 10 melts in solderand the columnar bump 6 is joined to the pad 14 through solder fillet 11as shown in FIG. 31B, then filled up with the underfill resin 17thereafter and cured as shown in FIG. 31C.

This embodiment relates to a packaging method for a semiconductorelement shown in FIG. 7. In this embodiment, while gold film 10 isformed on the surface of the solder plating film 9 provided on an upperpart of a columnar projection 6, gold film 10 is formed also on a pad 14as shown in FIG. 30 A. By forming these gold films, the surface of asolder plating film 9 and a pad 14 is held in a clean state withoutoxidizing. After aligning a semiconductor element so that the columnarbump 6 may be located on the pad 14, if a semiconductor element iscarried on a wiring substrate 12 an d subjected to solder reflowprocess, the gold film 10 melts in solder and the columnar bump 6 isjoined to the pad 14 through solder fillet 11 as shown in FIG. 30B, thenfilled up with the underfill resin 17 thereafter and cured as shown inFIG. 30C.

FIGS. 32A to 32C are cross-sectional views of a process order showing afourteenth embodiment of a producing method for a semiconductor deviceof this invention. The surface of a semiconductor element and a wiringsubstrate is exposed in the plasma atmosphere of inactive gas, such asargon, and the junction side of a pad 14 with a columnar bump 6 is madeclean as shown in FIG. 32A. After alignment, the semiconductor elementis carried on a wiring substrate 12, pressurized and the columnar bump 6tip part is stuck to the pad 14 by pressure as shown in FIG. 32B. Atthis time, either of the means of heating or ultrasonic wave, orcombined use of the both may be adopted. Then, underfill resin 17 ispoured in and cured as shown in FIG. 32C.

FIGS. 33 A to 33C are cross-sectional views of a process order showing afifteenth embodiment of a producing method for a semiconductor device ofthis invention. In this embodiment, a cap film 8 composed of gold etc.is formed beforehand on a pad 14 of a wiring substrate. Difference froman eleventh embodiment shown in FIG. 32 in this embodiment resides onlyin a form such that the cap film 8 is formed on the pad 14, to therebyomit a detailed explanation.

In this embodiment, a cap film 8 was formed only in the pad side of awiring substrate, the cap film can be conversely formed only in acolumnar bump side. Also, like an eleventh embodiment and a twelfthembodiment, when a cap film is not formed on at least one junction sidesurface, the junction can more preferably be performed in a vacuum ornon-oxidizing atmosphere. That is, it is more preferable to maintainenvironment in a vacuum or non-oxidizing atmosphere state from acleaning processing until junction is performed by plasma.

FIGS. 34A to 34C are cross-sectional views of a process order showing asixteenth embodiment of a producing method for a semiconductor device ofthis invention. In this embodiment, for a semiconductor element, a capfilm 8 is formed on an upper surface of a columnar bump 6, and the capfilm 8 is also prepared on a pad 14 of a wiring substrate beforehand.Difference from a eleventh embodiment shown in FIG. 32 in thisembodiment resides only in a formation such that the cap film 8 isformed on the columnar bump 6 or the pad 14, to thereby omit a detailedexplanation. (see example 3)

Now examples of the present invention will be explained in conjunctionwith the drawings.

EXAMPLE 1

Referring to an example 1 of this invention, a producing method for asemiconductor element will now be described with reference to FIG. 9.

First, a cover film 3 of a silicon oxide film is formed on a wiringlayer of the aluminum alloy formed on a semiconductor substrate 1, and acover coat removal on an electrode 2 formed on the wiring layer tip partis carried out. Next, titanium as an interconnected film 4, and a copperfilm as an adhesive film 5 are formed on the whole surface in a orderlymanner by sputtering. Thickness of the cover coat film is determined as4.5 μm, thickness of the interconnected film is determined as 60 nm, andthickness of the adhesive film is determined as 500 nm. Next, a platingresist film 19 is formed and copper is deposited as a columnar bump 6 byelectrolytic plating. At this time, the size of the columnar bump isdetermined as about 140 μm in diameter, and about 90 μm in height.Subsequently, gold-plating is carried out and the cap film 8 of about0.1 μm thickness is formed on the columnar bump upper surface. And afterexfoliating plating resist, unnecessary portions of an adhesive film andan interconnected film are removed by wet etching, using a copper bumpas a mask. Then after being subjected to heat-treatment in oxidizingatmosphere, and a wet prevention film 7 is formed on a columnar bumpside, copper columnar bump formation is completed. The wet preventionfilm 7 may be formed immediately after plating resist exfoliation.

Next, a packaging method onto a wiring substrate of a semiconductorelement which has a copper columnar bump will be explained withreference to FIG. 20. First, flux 15 is uniformly applied in about 40 μmthickness by squeezing on smooth and flat plates such as a glass board.Then, a columnar bump is pushed and flux is transferred to a tip. Amethod for making flux being transferred may be a pin transferringmethod which transfers the flux on a pin. The method is not restrainedin the range in which the stable supply to a tip of a copper bump ispossible. And a semiconductor chip is mounted onto a wiring substratethereafter. Tin/eutectic lead alloy solder paste is supplied to thewiring substrate beforehand by printing on a pad part. Then after solderreflow process, the plate is pushed in parallel with a board surface andthe solder upper part is crushed, so that the height may be uniform.Next, after aligning a semiconductor element so that a columnar bump maybe located on a pad of a wiring substrate, the semiconductor element iscarried on a wiring substrate. Then with the semiconductor elementsubjected to solder reflow process and pressed simultaneously, acolumnar bump 6 is connected to a pad 14 of a wiring substrate. As for ajunction form of a semiconductor element and a wiring substrate, a capfilm which is good in solder wettability is formed only on an uppersurface of a columnar bump. And since wet prevention film is formed onthe side surface, solder does not turn around to the side and only anupper surface of a columnar bump joins to the pad. Namely, a solder doesnot get wet upwardly of a columnar bump as far as the part between thecolumnar bump and an adhesive film, or between the adhesive film and aninterconnected film, resulting in junction strength fall, norconstituting a stress concentration part like constriction form. Thiscontributes to having a reliable structure. Next, after cleaning andremoving flux 15, underfill resin 17 is poured in from the side. Then,after filling and curing, packaging of a semiconductor element iscompleted. In this embodiment, solder paste is supplied to the wiringsubstrate first to be melted and solidified once thereon, before theflip chip is mounted thereto. However, without melting and solidifyingsolder paste, the flip chip can also be carried in and joined.

EXAMPLE 2

As for a second example of the present invention, a producing method fora semiconductor element will be explained in conjunction with FIG. 10.In a similar manner to a first embodiment, as shown in FIG. 10B, on anelectrode 2, an interconnected film of 60 nm in thickness, and anadhesive film of 500 nm in thickness, and a columnar bump 6 withdiameter of about 140 μm and height of 90 μm, are formed, then subjectedto etching processing by oxygen plasma onto a plating resist film 19.Then, an upper portion of the columnar bump is exposed by about 15 μmand plated with gold, to thereby form a cap film 8 of about 0.1 μm inthickness. Subsequently, plating resist is exfoliated and chemicalremoval of the unnecessary portions of an adhesive film and aninterconnected film is carried out by wet etching using a columnar bumpas a mask, and subjected to heat treatment in oxidizing atmosphere. Awet prevention film 7 is thus formed on a copper columnar bump sidesurface. Next, a packaging method onto a wiring substrate of asemiconductor element having a columnar bump formed in an aforementionedmanner will be explained in conjunction with FIG. 25. As shown in FIG.25A, a solder film 16 is formed on a pad of the wiring substratebeforehand and along with this, flux 15 is applied to a tip part of acolumnar bump 6. Next, after aligning a semiconductor element so that acolumnar bump may be located on a pad of a wiring substrate, thesemiconductor element is carried on a wiring substrate. Then with asemiconductor element subjected to solder reflow process and pressedsimultaneously, a columnar bump 6 is connected to a pad 14 of a wiringsubstrate. As for a junction form of a semiconductor element and awiring substrate, since a cap film which is good in solder wettabilityis formed in a part of an upper surface and side surface of a columnarbump, and a wet prevention film is formed on the side surface, so as tobe formed in such a manner that solder fillet 11 wraps in an upperportion of the columnar bump. And a situation such that solder gets wetupwardly as far as a base of the columnar bump does not occur. Next,after cleaning and removing flux 15, underfill resin 17 is poured infrom the side, to be cured after filling. Packaging of a semiconductorelement is thus completed.

EXAMPLE 3

As a third example of the present invention, a producing method for asemiconductor element will now be explained in conjunction with FIG. 12.Similar to a first embodiment, after forming a cover coat, sputtering ofchromium/copper as an interconnected film 4, and copper as an adhesivefilm 5 is performed, so that an interconnected film and an adhesive filmmay be formed on the whole surface. An interconnected film 4 is definedas 100 nm in thickness, and an adhesive film 5 is defined as 500 nm inthickness. After forming a plating resist film 19 and forming a columnarbump 6 of copper with a diameter of about 140 μm, and a height of about90 μm by electrolytic plating, etching processing is performed by a drymethod and an upper part of the copper bump is exposed using thedifference of the etching speed of plating resist and copper. The heightof the portion to be exposed was set as about 15 μm. Next, the solderplating layer 9 of the eutetic alloy of 96.5% weight of tin and 3.5%weight of silver is formed on a copper bump by electrolytic plating inthe thickness of about 15 μm.

Since the solder plating film 9 is formed also on a columnar bump sidesurface at this time, control of film thickness is important so that theshort-circuit between electrodes may not take place at the time of nextfusion connection. Next, plating resist exfoliation is carried out andan excessive interconnected film and adhesive film are removed by wetetching, before subjected to a heat-treatment in oxidizing atmosphere,so that a wet prevention film 7 may be formed on the columnar bump 6side surface. Then, an oxide film formed on the solder plating film 9 isremoved by being subjected to plasma processing.

Next, a packaging method for a semiconductor element formed in theabove-described manner onto a wiring substrate will be explained inconjunction with FIG. 28. Activity resin 18 is uniformly applied on thetip of the solder plating film 9 on a copper bump in thickness of about40 μm, by squeezing on flat and smooth plates such as a glass board. Acolumnar bump is pushed against this and thermosetting resin (activityresin 18) is transferred on the tip. The method for making activityresin transferred is not restrained in the range in which the stablesupply to the tip of columnar bumps such as pin transfer, is possible.

Usually, flux is used for the oxide film removal on the surface of abump. As for a flux cleaning after packaging, introduction of specialcleaning equipment is needed to clean a narrow crevice between asemiconductor element and a wiring substrate. This requires a longercleaning time and may be considered as a causative factor of pushing upthe cost. Moreover, the cleaning residual substance is easy to remain,constituting one factor of a reliability fall. Also, by fine pitchtendency from now on it is expected that crevice cleaning becomes stillmore difficult. If activity resin is used like this embodiment, it iseffective in respect of a reduction of man-hour and plant-and-equipmentinvestment, improvement in the product yield, and improvement inpackaging reliability by saving the cleaning.

After applying activity resin 18, a semiconductor element is aligned andcarried on a wiring substrate, to be subjected to solder reflow process,and a columnar bump and a pad of a wiring substrate are connected. Acrevice is filled up with underfill resin at the end and cured, and thepackaging process of a semiconductor element is completed.

Activity resin is transferred and mounted here, flux may be usedreplacing the activity resin. Also, if gold is thinly plated on thesolder film formed on the columnar bump, junction will improve further,to the extent that junction is achieved without using flux.

In this embodiment, very-small-quantity transfer of the activity resinwas carried out onto the tip of a bump, and filled up with underfillresin thereafter. If the activity resin with reliability which is higherthan equivalent of underfill resin is used, resin filling can also berealized without performing resin pouring in such a manner that a properquantity of activity resin is supplied to a wiring substrate, asemiconductor chip is carried onto a board, and resin curing is alsoperformed at the time of the solder reflow process. Also, in cases ofthe embodiments 1 to 3, a resin film may be provided on a pad, solderfilm, and a solder plating film for the purpose of an oxidationprevention. Furthermore, instead of the flux which was transferred to abump tip and used for connection, the activity resin having a fluxeffect which is cured by the quantity of heat at the time of junctionand reinforces connection part after connection, is also possibly used.

EXAMPLE 4

Referring to a fourth example of the present invention, a producingmethod for a semiconductor element will next be explained in conjunctionwith FIG. 2. First, silicon oxide is deposited all over thesemiconductor substrate 1, and the cover film 3 is formed. A partthereof is removed and the surface of an electrode 2 made from aluminumalloy is exposed, before sputtering of the copper film is carried out inan orderly manner, determining titanium as an interconnected film 4, anddetermining copper film as an adhesive film 5. The interconnected filmand the adhesive film are thus formed on the whole surface. Thethickness of the cover coat is set as 4.5 μm, the thickness of theinterconnected film is set as 60 nm, and the thickness of the adhesivefilm is set as 500 nm. Next, the plating resist film 19 was formed andcopper was deposited by electrolytic plating to obtain a columnar bump6. The size of the columnar bump is set as about 140 μm in diameter, andabout 90 μm in height. Subsequently, a cap film 8 of about 5 μmthickness is continuously formed on the columnar bump upper surface bygold-plating. Then, plating resist is exfoliated and unnecessaryportions of an interconnected film and an adhesive film are removed bywet etching, using a copper bump as a mask. Wet prevention film is notformed in this example.

A packaging process onto a wiring substrate of a semiconductor elementhaving a copper bump will next be explained in conjunction with FIG. 34.In this embodiment, a cap film 8 (gold plating film) is formed on a pad14 of a wiring substrate 12, also. Just before carrying a semiconductorelement onto a wiring substrate, argon plasma cleaning is carried out toa semiconductor element and a wiring substrate. The semiconductorelement and the wiring substrate are aligned thereafter, and thesemiconductor element is carried onto the wiring substrate. Then, theload of about five to 50 gf (0.049-0.49 N) per bump is applied, andsimultaneously heated at 350 degrees, so that a junction between a bumpand a pad may be achieved. Here, there is no necessity of cleaning sinceflux is not used. Immediately after this, underfill resin is poured infrom the side, to obtain a cured resin after filling.

As in the foregoing, since connection to a pad on a wiring substrate iscarried out using a small amount of solder or without using solder,alpha dose leading to a soft error can be reduced, and improvement inreliability can be aimed at. Also, since the part joined to solder of acolumnar bump is limited to the upper surface of the columnar bump, orthe bump side surface in the vicinity of the upper surface. Whereby, thediameter of the bump is not needed to be thick even if a bump becomeshigh, and the distance between the semiconductor board and the wiringsubstrate can be secured, responding to high pin count. Accordingly,even if high-density tendency of LSI advances according to thisinvention, filling of underfill resin can be easily and reliably carriedout. In addition, according to this invention solder does not get wetupwardly as far as the base of the columnar bump resulting in junctionintensity fall between the columnar bump and the adhesive film, orbetween the adhesive film and the interconnected film. Improvement inreliability can thus be aimed at.

Since a columnar bump of this invention is formed by the electrolyticplating method etc. in a wafer stage, manufacture at low cost comparedwith a solder ball loading method is possible. Also, according to anembodiment which uses the thermosetting resin (activity resin) which hasthe flux activity effect instead of the flux used at the time of flipchip mounting, improvement in reliability by low cost by cleaningprocess reduction and an elimination of cleaning residual substance, isrealized.

1. A method of producing a semiconductor element, comprising the stepsof: forming a metal film serving as a plating electrode on the wholepart of a semiconductor substrate having an electrode formed thereon;forming a resist film having an opening in the position of saidelectrode on said metal film; depositing a high conductivity metal incolumnar form to form a columnar projection by electrolytic plating;removing said resist film; etching to remove said metal film by usingsaid columnar projection as a mask; and forming a wet prevention film onthe surface of said columnar projection.
 2. The method of producing asemiconductor element as set forth in claim 1, wherein after forming ofsaid wet prevention film on the surface of said columnar projection,said wet prevention film on the part of said columnar projectionconnected to a packaging substrate is removed.
 3. A method of producinga semiconductor element, comprising the steps of: forming a resist filmhaving an opening in the position of said electrode on a semiconductorsubstrate having an electrode thereon; forming an activation processinglayer by activation processing to electroless plating; removing saidactivation layer on the said resist film; depositing highly conductivemetal in said opening by electroless plating to form a columnarprojection; removing said resist film; and forming a wet prevention filmon the surface of said columnar projection, wherein after forming ofsaid wet prevention film on the surface of said columnar projection,said wet prevention film on the part of said columnar projectionconnected to a packaging substrate is removed.
 4. The method ofproducing a semiconductor element as set forth in claim 1, whereinbefore forming of a wet prevention film on the surface of said columnarprojection, a mask is formed on a region of said columnar projectionwhere said wet prevention film should not be formed, and after formingof a wet prevention film on the surface of said columnar projection,said mask is removed.
 5. A method of producing a semiconductor element,comprising the steps of: forming a resist film having an opening in theposition of said electrode on a semiconductor substrate having anelectrode thereon; forming an activation processing layer by activationprocessing to electroless plating; removing said activation layer on thesaid resist film; depositing highly conductive metal in said opening byelectroless plating to form a columnar projection; removing said resistfilm; and forming a wet prevention film on the surface of said columnarprojection, wherein before forming of a wet prevention film on thesurface of said columnar projection, a mask is formed on a region ofsaid columnar projection where said wet prevention film should not beformed, and after forming of a wet prevention film on the surface ofsaid columnar projection, said mask is removed.
 6. The method ofproducing a semiconductor element as set forth in claim 1, wherein saidwet prevention film is a silicon oxide film or a silicon nitride filmdeposited by a CVD method.
 7. A method of producing a semiconductorelement, comprising the steps of: forming a resist film having anopening in the position of said electrode on a semiconductor substratehaving an electrode thereon; forming an activation processing layer byactivation processing to electroless plating; removing said activationlayer on the said resist film; depositing highly conductive metal insaid opening by electroless plating to form a columnar projection;removing said resist film; and forming a wet prevention film on thesurface of said columnar projection, wherein said wet prevention film isa silicon oxide film or a silicon nitride film deposited by a CVDmethod.
 8. The method of producing a semiconductor element as set forthin claim 1, wherein said forming of said wet prevention film on thesurface of said columnar projection is exposing said columnar projectionto oxidizing atmosphere to form an oxide film on the surface of saidcolumnar projection.
 9. A method of producing a semiconductor element,comprising the steps of: forming a resist film having an opening in theposition of said electrode on a semiconductor substrate having anelectrode thereon; forming an activation processing layer by activationprocessing to electroless plating; removing said activation layer on thesaid resist film; depositing highly conductive metal in said opening byelectroless plating to form a columnar projection; removing said resistfilm; and forming a wet prevention film on the surface of said columnarprojection, wherein said forming of said wet prevention film on thesurface of said columnar projection is exposing said columnar projectionto oxidizing atmosphere to form an oxide film on the surface of saidcolumnar projection.
 10. The method of producing a semiconductor elementas set forth in claim 2, wherein said removing of said wet preventionfilm in the connection part of said columnar projection corresponds toexposing said columnar projection to plasma of inactive gas.
 11. Themethod of producing a semiconductor element as set forth in claim 1,wherein after forming of said columnar projection and before removingsaid resist film, a solder film is coated on the upper surface of saidcolumnar projection.
 12. The method of producing a semiconductor elementas set forth in claim 1, comprising the steps of; after forming of saidcolumnar projection and before removing of said resist film, exposingthe upper portion of side surface of said columnar projection byapplying half-etching onto said resist film; and coating the uppersurface and the upper portion of side surface with solder film.